(a) Field of the Invention
The present invention relates to a method and server for estimating the position of a mobile node, and more particularly, to a method for estimating the position of a mobile node by using anchor nodes that know their position information.
(b) Description of the Related Art
Positioning systems include a Global Positioning System (GPS), Inertial Navigation System (INS), LORAN (Long Range Aid to Navigation), RFID/USN (Radio Frequency Identification/Ubiquitous Sensor Network), and a method using wireless/mobile communication infrastructures.
Moreover, services using positioning include a method of estimating the position of a home node to get a service and a method of estimating the position of a foreign node to get a service. In these services, if position information of the foreign node is required, the home node wirelessly receives its own position information, calculated by the foreign node, from the foreign node, or receives a signal reflected by a transmitted signal, such as a radar signal, and calculates the position information of the foreign node, or receives the position of the foreign node from a position calculation server.
In general, GPS is most commonly used for positioning. However, the GPS does not work indoors, buildings, forests, and so forth because a GPS signal is blocked, and can give wrong position information due to a jammer.
When the GPS cannot be used, the position of a mobile terminal can be estimated by a wireless communication infrastructure. To this end, multiple anchor nodes that know their exact installation position should be installed. However, it might be impossible to install and use the anchor nodes in a wide area due to the problems of cost, equipment availability, and the like.
Recently, a variety of position estimation technologies based on a wireless communication infrastructure have been developed to calculate the position of a mobile terminal. Wireless communication infrastructures used for position estimation include WLAN, ZigBee, Ultra Wideband (UWB), Chirp Spread Spectrum (CSS), etc. These infrastructures have limitations in constructing a position estimation system for service in a wide area because of their narrow transmission and reception coverage. Among these infrastructures, IEE 802.15.4a-based Impulse Radio-UWB (IR-UWB), which can be used for high-precision position estimation because it is capable of correctly estimating distance, has the drawback of a narrow coverage of about 20 to 30 m due to its limitation of transmission power. Therefore, in attempting to provide a location-based service in wide indoor and outdoor areas based on such an wireless communication infrastructure, there is a difficulty of installing a large number of anchor nodes in an overlapping manner.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.